FlipperDotNet

A .Net port of the client portion of the feature flagging Flipper project.

In addition to fully enabling or disabling features, it allows enabling for a percentage of users, a percentage of time, or specific users.

The current backend stores are in-memory, Consul, and Redis.

TODO: enable by groups.

Installation

FlipperDotNet is available as a NuGet package. Include the adapter package that you are using, either FlipperDotNet.Consul or FlipperDotNet.Redis. They will include the core package FlipperDotNet.Core

Source code is available at https://github.com/paybyphone/flipperdotnet

General Usage

Each instance of the client caches values to reduce traffic. Each request should create a new client.

Instantiating the client

using FlipperDotNet;
using FlipperDotNet.Adapter;

var adapter = new MemoryAdapter();
var flipper = new Flipper(adapter);

That's it! You will be using an in-memory adapter for the client.

Adapter Exceptions

All exceptions thrown by the underlying adapter are wrapped in an AdapterRequestException, with the original being passed in the InnerException property.

Setting Features

Features can be fully enabled or disabled from the client using

flipper.Enable("search");
flipper.Disable("search");

For more complex settings, use access the feature

var searchFeature = flipper.Feature("search");

searchFeature.Enable();
searchFeature.Disable();

searchFeature.EnablePercentageOfTime(10);
searchFeature.DisablePercentageOfTime();

searchFeature.EnablePercentageOfActors(25);
searchFeature.DisablePercentageOfActors();

"Actors" are a generic term for users. Non-person users of a service can also be represented by a Actor. Actor classes implement the IFlipperActor interface.

public interface IFlipperActor
{
    string FlipperId { get; }
}

FlipperId returns a string representation of the Id for the actor.

class MyActor : IFlipperActor { ... }

var myActor = new MyActor(...);
searchFeature.EnableActor(myActor);
searchFeature.DisableActor(myActor);

Checking Features

To check if a feature is enabled

searchFeature.IsEnabled;

will return True if the feature is fully enabled or if the percentage of time check matches.

To check for an actor

searchFeature.IsEnabledFor(myActor);

will return True if the feature is fully enabled or any of the following are enabled:

• for the percentage of time,
• for the percentage of actors, or
• for the specific actor

Collecting Statistics

FlipperDotNet can collect timing and count statistics using Statsd or compatible systems.

Pass an Instrumenter when creating the Flipper object.

var statsdClient = new Statsd("localhost", 8125);
var instrumenter = new StatsdInstrumenter(statsdClient);
var flipper = new Flipper(adapter, instrumenter);

Using the Consul Adapter

The Consul adapter uses the Consul.NET client.

using FlipperDotNet.ConsulAdapter;

var client = new Consul.Client();
var adapter = new ConsulAdapter(client);
var flipper = new Flipper(adapter);

Since Consul is intended to be set up as a single global cluster in one datacentre, with possible replication between datacentres, the flipper data can (and should) be namespaced:

var adapter = new ConsulAdapter(client, "my/flipper/name/space");

Using the Redis Adapter

The Redis adapter uses the StackExchange.Redis client.

Note: The NuGet package does not work on Mono. According to this issue, when using Mono, download the code and build it using monobuild.bash.

using FlipperDotNet.RedisAdapter;

var multiplexer = ConnectionMultiplexer.Connect("localhost,allowAdmin=true");

var	database = multiplexer.GetDatabase();
var adapter = new RedisAdapter(database);
var flipper = new Flipper(adapter);